The G20 could suffer reputational damage if Australia prevents climate change from making it onto the final communique at the Leaders Summit in November, an expert has warned.

The Lowy Institute's Hugh Jorgensen says despite the federal government's decision to keep climate change off the agenda for the G20 Leaders Summit later this year, nothing will stop leaders such as US President Barack Obama from talking about the issue when they come to Australia.

High-level talks about the topic will still be held behind closed doors and woven into discussions on official topics such as energy, infrastructure and finance, he said.

But the G20's reputation as a premier global economic governance forum could be damaged if climate change was not referenced in the forum's final communique, he warned.

''It would be regrettable if the reputation of the G20 took a hit under Australia's presidency because of the omission of climate change from the agenda,'' Mr Jorgensen said.

''Whether that happens will depend on the final communique and how well the Prime Minister and other G20 leaders are able to explain to the public why they focused on the issues they did, and not others,'' Mr Jorgensen said.

Mr Obama has made a concerted effort in recent weeks to put climate change action back on the global agenda by pushing for coordinated action through forums such as this year's G20.

But Prime Minster Tony Abbott and conservative Canadian Prime Minister Stephen Harper have this week signalled intentions to create a centre-right alliance of countries - including Australia, Canada and Britain - to prevent international moves to address climate change through carbon trading.

Mr Jorgensen, a research associate at the Lowy Institute's G20 Studies Centre, which was set up with federal funding, said though the Abbott government should be commended for focusing on a ''tightened agenda'' at this year's G20, the fact that the summit was be held just one month before climate talks in Peru meant it was a good opportunity to focus the collective attention of world leaders onto climate change.

It comes after a Lowy Institute poll last week found 45 per cent of Australian adults now say ''global warming is a serious and pressing problem'' and that ''we should begin taking steps now even, if this involves significant costs''.

The concern is up 5 percentage points since 2013 and 9 points since 2012, the Lowy Institute says.

Dr Susan Harris-Rimmer from ANU's College of Asia and the Pacific said climate change will only be on the G20 agenda in ''subtle ways'' in November because its member countries decided that the negotiating space for climate change should be the United Nations Framework Convention on Climate Change, which takes place in December.